An electrical power system powers loads (such as electronic equipment) by delivering voltage to the loads through a power bus. The power system has an anticipated normal voltage operating range for its power bus. Loads powered by that bus are expected to operate correctly and without damage over that range. Disturbances to the power system, including but not limited to misconnections, broken electrical connections, and sudden switching ON or OFF of inductive load elements, can perturb the power bus with peak positive voltages that may greatly exceed the normal voltage operating range, or alternately may drive the voltage on the power bus negative.